In recent years, needs for flat panel displays (FPD) have increased with the development of highly-information oriented societies. Examples of the flat panel displays include a non-self-luminous liquid crystal display (LCD), a self-luminous plasma display (PDP), an inorganic electroluminescence (inorganic EL) display, and an organic electroluminescense (hereinafter, also referred to as an “organic EL” or an “organic LED”) display.
Among these flat panel displays, the liquid crystal display has generally enhanced viewability by providing an illumination device as a light source on the rear surface of a transmitting liquid crystal display element and illuminating the liquid crystal element from the rear surface thereof.
According to such a liquid crystal display, outgoing light from the light source is generally unpolarized light. 50% or more of the outgoing light is absorbed by a polarizer arranged on an illumination light incident side of the liquid crystal display element, and efficiency of using the light from the light source is low. In addition, in a color liquid crystal display device in which a white light source is used as a light source and micro color filters corresponding to three primary colors or four primary colors are arranged in a display surface and which performs color display by additive process, over 70% of the light is absorbed by the color filters. Accordingly, efficiency of using the light from the light source is low, and an improvement in efficiency of using the light has been required.
In order to solve such a problem, PTLs 1 and 2 disclose the following color display devices, for example. The color display devices include a pair of transparent substrates, a liquid crystal layer, a liquid crystal display element, an illumination device, a first wavelength transformation phosphor, a second wavelength transformation phosphor, and a color filter. The pair of transparent substrates is arranged with a certain gap such that transparent electrode formation surfaces face each other. The liquid crystal layer is held between the transparent substrates. The liquid crystal display element includes voltage application means for applying a voltage corresponding to an image signal to pixels in a matrix shape, which are formed by transparent electrodes of the pair of transparent substrates. The illumination device emits light from a blue range to a blue green range. The first wavelength transformation phosphor emits red light by using the light from the blue range to the blue green range as excitation light. The second wavelength transformation phosphor emits green light by using the light from the blue range to the blue green range as excitation light. The color filter cuts light other than the blue range to the blue green range.
According to the aforementioned configuration, it is possible to use blue light emitted from a blue light source as it is for a pixel displaying blue color and to thereby enhance efficiency of using light.
However, according to the liquid crystal display device which uses the blue light source, when an image displayed is viewed from an oblique direction, the image has a yellowish tone, and a view angle color display property deteriorates.
Accordingly, PTL 3 discloses the following liquid crystal display device, for example. The liquid crystal display device includes a blue light source, a liquid crystal element, a color filter, and a light-scattering film. The blue light source emits blue light. The liquid crystal element includes a liquid crystal cell and a pair of polarizers which holds the liquid crystal cell therebetween. The color filter includes first and second phosphors. The first phosphor is excited with the blue light and emits red fluorescence. The second phosphor is excited with the blue light and emits green fluorescence. The light-scattering film scatters at least the blue light.
In addition, PTL 4 discloses a light-diffusing sheet, in which light-diffusing particles configuring a light-diffusing sheet are composed of first particles and second particles with a higher refractive index and a smaller grain size as compared with the first particles, a light-diffusing performance of which is thus enhanced, and which prevents occurrence of variations in luminance.